Distal Biceps Rupture or Avulsion
The Biceps muscle lies at the front of the upper arm. It originates from two points on the shoulder blade (Scapula) and extends to the forearm where it attaches to the Radius (one of the two forearm bones).
The Biceps crosses both the shoulder and elbow joints. The Biceps forward flexes the shoulder but also flexes the elbow. While we often think of the Biceps muscle as an elbow flexor, such as a during a ‘Biceps curl’, the main role of the Biceps is actually supination of the forearm (rotating the forearm from palm down to palm up).
Tears of the Biceps tendon at the elbow are uncommon. They may be partial or complete. They often occur when the elbow is forced straight against resistance. When the tendon tears completely, it typically comes off the bone and pulls back up the arm causing bunching of the Biceps muscle. Once torn the tendon will not heal or re-attach it self.
The strength of elbow flexion will typically be reasonably preserved although a bit weak. The biggest loss of strength is in supination, which is the action of turning the hand over from palm down to palm up.
Surgery affords the opportunity of re-attaching the tendon and improving strength, however, conservative or non-operative management often results in reasonable function.
Long Head Biceps Tears
The Biceps may also tear at the shoulder, where the Long Head Biceps tendon ruptures. This is the smaller of the two proximal tendons. This does not typically cause significant functional impairment. The Biceps muscle will bunch downwards slightly. The significance of Long Head Biceps tendon tear is that there may be an associated tear of the rotator cuff tendons, which may go unappreciated.
Anatomy
The Biceps starts with two tendons at the shoulder. The main tendon is the Short Head Biceps that originates from the Coracoid process of the Scapula (shoulder blade). The Long head Biceps is a small but long tendon that starts at the top of the Glenoid (the shoulder socket).
The two top tendons merge to form the Biceps muscle. The distal tendon at the elbow attaches on to the Radius, one of the two bones that make up the forearm. It attaches on to a prominence or bump on the radius called the Radial Tuberosity. This enhances the rotation obtained on Biceps contraction.
The Brachialis lies under the Biceps and is a strong muscle that is the principal flexor of the elbow. A number of other muscles cross the elbow and also contribute to elbow flexion. In addition there are other muscles that supinate or rotate the forearm.
Presentation
There may be a pop or snap as the tendon fails.
There may be bruising and swelling at the front of the elbow.
The biceps typically becomes more pronounced as it bunches upwards.
There is often pain and/or weakness on elbow flexion or supination (forearm rotation form palm down to palm up).
There is often a gap in the normal contour of the Biceps, above the elbow, where the Biceps has retracted.
There may be some puckering of the skin above the elbow on Biceps contraction because of tethering of the retracted torn tendon to the overlying skin and soft tissues.
Examination
Examination of the elbow involves inspection of the elbow and palpation of the Biceps and the position of the tendon. Whilst the diagnosis is often clear this is not always case. The Brachialis tendon will remain intact and may be confused with the Biceps tendon giving the false impression that the Biceps remains intact. Strength may be compared, although pain may limit the assessment of this, particularly early on.
Investigation
Possible investigations include X-Rays, Ultrasound and Magnetic Resonance Imaging.
The X-Rays will not demonstrate the soft tissues or tendon tear but may provide information regarding the potential joint arthritis or bony injury. An Ultrasound or MRI will image the softy tissues and help identify the tendon tear and its location.
Treatment
Conservative management is reasonable and may give satisfactory function accepting some weakness of elbow flexion and more significantly supination.
Surgery offers the opportunity of reattaching the tendon and improving strength and stamina, although there are some risks associated with the surgery, particularly the risk of nerve injury.
Non-operative management
This typically involves analgesics and anti-inflammatories initially. A graduated rehabilitation program, to optimise strength in the remaining muscle groups, follows initial rest and support. Day-to-day and sporting activities can be reintroduced as tolerated.
Surgical treatment
Surgery is normally undertaken within the first 3 weeks after injury. Repair after this time is often possible but there is an increasing risk of scarring and shortening of the Biceps, potentially limiting the possibility of repair and the outcome of repair if achieved.
Late repair may be achievable although the outcome will be less predicable. A tendon graft may be used to bridge shortening of the tendon.
There are a number of different techniques for fixing the tendon both in terms of incision (scar) and means of re-attachment.